The present invention relates to improvements in engine block heaters for internal combustion engines. In particular, it relates to the improvements and method of retaining the heaters in the core hole of an automotive engine block.
In the construction of internal combustion engines adapted to be water-cooled, it is common practice to cast the cylinder block and water jacket in one piece using sand molding. Apertures are provided for the removal of sand following the casting operation; when the engines are finally assembled, the apertures may be sealed with suitable dished plates.
Commonly, these apertures may be used for fitting electrical heating means into the engine. Some prior art engine block heaters finding particular application in automobile engines are disclosed in Canadian Pat. No. 842,973 issued May 26, 1970 to L. E. Windsor and Canadian Pat. No. 850,767 issued Sept. 1, 1970 to C. A. Ehgoetz. In the engine block heaters disclosed in these patents, a straight yoke or clamping assembly is employed to fasten the plug member of the block heater in sealed relation within the block aperture. A screw passes either loosely through the plug member of the heater or through the elongated straight yoke. As a result, either the screw or the yoke may be canted to facilitate the insertion of the yoke through the block aperture. Once inserted, the screw is manipulated to draw the yoke back towards one face of the plug member, bringing the ends of the yoke member into engaging relation with interior wall portions of the engine block to rigidly secure the heater within the block aperture.
While engine block heaters as described hereinabove are still in use, these heaters are not well suited for use in automobile engines having special limitations in the size of the engine block. A number of heaters have been developed for use in automobile engine blocks having special limitations, and are disclosed in U.S. Pat. No. 3,766,356 issued Oct. 16, 1973 to Feldmann; U.S. Pat. No. 4,175,229 issued Nov. 20, 1979 to Brinkhof et al; and Canadian patent application No. 336,783 filed Sept. 28, 1979 in the name of Brinkhof et al. Each of the engine block heaters described in these references has a yoke or clamping assembly normally having an outside diameter less than the diameter of the aperture provided in the engine block so as to facilitate insertion of the yoke assembly through the aperture into the engine block. A screw and a pressure bar are provided for deforming the yoke assembly. The screw is attached to the pressure bar which may be drawn toward one surface of the plug member of the heater to deform the yoke assembly. Once deformed, the yoke assembly has an outside diameter that is larger than the diameter of the aperture in the block wall of the engine block. The pressure bar holds the deformed yoke assembly against the block wall so as to maintain the heater in secured relation with the engine block. The removal of this type of heater involves loosening the screw, moving the pressure bar and yoke assembly away from the plug member, and subsequently pulling the heater out of the engine block causing the yoke assembly to deform a second time into a diameter less than that of the aperture of block. Deformation of the yoke assembly occurring during repeated insertion and removal of the engine block heater stresses the material of the yoke assembly. In practice, the yoke assembly allows for insertion and removal of the heater a limited number of times.
Engine block heaters which can be inserted and removed from an engine block a repeated number of times are disclosed in Canadian Pat. No. 854,325 issued Oct. 20, 1970 to L. E. Windsor, and Canadian patent application Ser. No. 389,875 filed Nov. 12, 1981 in the name of Y. Y. Chang et al. These block heaters rely on pivotal movement of the wing portions of the yoke or clamping assembly to change the outside diameter of the yoke assembly from a diameter that facilitates the insertion of the yoke assembly into the engine block to a diameter that allows the ends of the yoke assembly to be brought into engaging relation with interior wall portions of the block. These block heaters do not provide the simplicity provided by some of the block heaters having deformable yoke assemblies.
Another form of engine block heater disclosed in Canadian Pat. No. 870,788 issued May 11, 1971 to W. H. Wernicke, has a spring material normally biased in a bow. A screw passes through the plug member and the spring material. When the screw is manipulated to draw the spring material back toward the plug member, the edges of the bow material bite into the side of the aperture. The problem associated with this block heater is that the strength of the spring material must be considerable to bite into the wall of the aperture and secure the plug member in the aperture. Further, while the spring means may be repeatedly used, the spring means is not operable in the event that the ends of the spring means are brought into engaging relation with interior wall portions of the block.
It is therefore an object of the present invention to provide a fastening assembly for an engine block heater that is relatively inexpensive and permits the engine block heater to be repeatedly inserted into and removed from the engine block.
Briefly, the present invention provides a heater suitable for use in an aperture of a block of an internal combustion engine. The heater comprises a plug member having a heating element extending from one side of the plug member. The plug member is adapted for insertion into the block aperture in sealing relation therewith such that the heating element is positioned in the block. A clamping means is provided for securing the plug member in the aperture. The heater also provides an adjustable means passing at least loosely through one of the plug member and clamping means for adjusting the position of the clamping means relative to the plug member. The clamping means includes an elongated flexible member having its ends normally biased such that the distance between the ends is greater than the diameter of the aperture. The flexible member is capable of bending in opposing directions to reduce the distance between its ends and facilitate insertion of the flexible member through the aperture. The clamping means also includes a rigid member securable in at least partial contacting and supporting relation with one side of the flexible member to prevent bending of the flexible member in one of said opposing directions. Thus, when the adjusting means is manipulated to draw the flexible member toward the plug member, the ends of the flexible member move into engaging relation with the interior wall portions of the block because the rigid member prevents the bending of the flexible member.
Further, the heater may be readily removed from the engine block by backing off the adjusting means and canting either the adjusting means or the clamping means depending on which one of the plug member or clamping means the adjusting means passes loosely through. It should be understood that should the adjusting means pass loosely through the plug member, a sealing O ring surrounding the adjusting means and the aperture of the plug member is provided to ensure a proper seal.
Additionally, in the preferred construction, the adjusting means comprises a screw which passes loosely through the plug member. In alternate constructions at least one of the flexible member and the rigid member is threadably secured with the screw. Preferably, both the flexible and rigid members are threadably secured with the screw.